1. Field of the Invention
The present invention relates generally to a robot cleaner, which has a charging battery, and an external charging apparatus for charging the charging battery, and more particularly, relates to a robot cleaner system that effectively performs a docking operation with an external charging apparatus and a method for docking a robot cleaner with the external charging apparatus.
2. Description of the Prior Art
Generally, a robot cleaner not only suctions dust and foreign substances from a surface to be cleaned while automatically traveling around an area to be cleaned without requiring manipulation of a user, but also operates as a house monitoring device that checks windows, gas valves, or the like.
Since the robot cleaner measures distances from its current location to obstacles like furniture, office appliances and walls, which are furnished in a working area, such as house or office, through a sensor, the robot cleaner can perform necessary work and can simultaneously avoid collisions with the obstacles.
Such a robot cleaner has a battery for supplying power necessary to drive the robot cleaner. Generally, the battery uses a charging battery that can be charged when the electric power of the battery has been consumed. Accordingly, one system comprising a robot cleaner and an external charging apparatus that charges the charge battery of the robot cleaner are provided.
The robot cleaner is also required to sense the location of the external charging apparatus so as to automatically return to the external charging apparatus when it is necessary to recharge the battery.
A conventional method of sensing the Location of the external charging apparatus requires the external charging apparatus to generate a high-frequency signal and the robot cleaner to receive the generated high-frequency signal, and the robot cleaner detects the location of the external charging apparatus based on the level of the received high-frequency signal.
However, this conventional method has a disadvantage in that there is a variation in the level of the high-frequency signal due to external factors, such as reflected waves and interference waves. Such factors cause variations in the level of the high-frequency signal that hinders accurate detection of the location of the external charging apparatus.
Moreover, even when the robot cleaner accurately detects the location of the external charging apparatus, it is often the case that the charging terminal of the robot cleaner cannot be accurately connected with a terminal of the external charging apparatus.
Accordingly, there has been requirement for a robot cleaner system and a method for docking a robot cleaner with an external charging apparatus that are capable of accurately detecting the location of the external charging apparatus and connecting the charging terminal of the robot cleaner with the terminal of the external charging apparatus.
The present invention has been developed in order to solve the above described problems in the prior art. Accordingly, an object of the present invention is to provide a robot cleaner system having an external charging apparatus and a method for docking a robot cleaner with the external charging apparatus that are capable of accurately detecting the location of the external charging apparatus and connecting a charging terminal of the robot cleaner with a terminal of the external charging apparatus.
The above object is accomplished by a robot cleaner system according to the present invention, including an external charging apparatus and a robot cleaner. The external charging apparatus includes a power supply terminal connected to a wire through which utility power is supplied, and a terminal stand for supporting the power supply terminal and fixing the external charging apparatus to a predetermined location. The robot cleaner includes a driving unit for moving a cleaner body, an upper camera disposed on the cleaner body for photographing a portion of the ceiling above the area in which the robot cleaner will be performing work, a charging battery disposed in the cleaner body for being charged by power supplied from the power supply terminal, a bumper disposed along an outer circumference of the cleaner body and outputting a collision signal when a collision with an obstacle has been detected, and a charging terminal disposed at the bumper to be connected with the power, and being connected to the charging battery. Prior to starting an operation, the robot cleaner photographs an upward-looking image using the upper camera, calculates the location information of the external charging apparatus, and stores the location information when it is connected to the external charging apparatus, and, when returning to the external charging apparatus, the robot cleaner calculates a return path based on the current location information calculated from an image photographed by the upper camera and the stored location information of the external charging apparatus and returns to the external charging apparatus along the return path.
The robot cleaner includes means to determine whether the charging terminal is connected with the power supply terminal only upon detecting a signal indicating contact of the charging terminal with the power supply terminal.
Preferably, the robot cleaner includes a battery charge detecting part for detecting the amount of electrical power available in the charging battery; and a control unit for controlling the driving unit to stop the operation and return the robot cleaner to the external charging apparatus when a charge requesting signal is received from the battery charge detecting part.
The control unit controls the driving unit to return the robot cleaner to the external charging apparatus when the commanded work is completed.
The terminal stand is formed to enclose a portion of the outer circumference of the bumper of the robot cleaner.
The above object according to the present invention is also accomplished by a method of docking a robot cleaner with an external charging apparatus, including the steps of receiving a work command signal; when a work command signal is received with the robot cleaner being connected with the external charging apparatus, calculating location information of the external charging apparatus based on an upward-looking image photographed by an upper camera and storing the location information; performing the work commanded by the work command signal while the robot cleaner travels from one area to another; when a charging command signal is received, calculating a return path to the external charging apparatus based on the current location information calculated from the upward-looking image photographed by the upper camera and the stored location information of the external charging apparatus, and then returning along the returning path; after the reception of a collision signal from a bumper, determining whether a contact signal is received or not, the contact signal indicating contact of a charging terminal of the robot cleaner with a power supply terminal of the external charging apparatus; when it is determined that the contact signal is not received after the collision signal is received from the bumper, adjusting an angle of travel of the robot cleaner by a predetermined angle to determine whether reception of the contact signal has been completed; and when it is determined that the contact signal is not received after a predetermined number of adjustments of the angle of travel, retreating the robot cleaner by a predetermined distance and then performing the steps of calculating the return path and returning.
The charging command signal is sent out when a predetermined amount of charged current amount runs out during the performance of the work or when the work is completed.
The predetermined angle for adjusting the angle of travel of the robot cleaner is 15xc2x0, and the number of adjustments of the angle of travel of the robot cleaner is six.
As described above, when the robot cleaner completes the commanded work or needs to be charged after being separated from the external charging apparatus, according to the robot cleaner system of the present invention having the external charging apparatus and the method for docking the robot cleaner with the external charging apparatus, the robot cleaner accurately returns to the external charging apparatus by using the stored location information of the external charging apparatus and the current location information. Also, since robot cleaner is docked with the external charging apparatus using a bumper signal and a contact signal of the charging terminal, the robot cleaner detects the location of the external charging apparatus accurately and connects the charging terminal to the external charging apparatus accurately.